The “fundamentally decent man” was provoked by pupils during a lesson in July last year, when they called him a “psycho” and “bald-headed bastard”. He lost control and hit the boy about the head with the 3kg weight while shouting “die, die, die”.

Following the sentencing, his union, the NASUWT, said it hoped the school’s governors and Nottinghamshire County Council would allow the married father-of-two to retire on the grounds of ill health.

But, the union said in a statement: “It is with deep regret that the NASUWT has to announce that the governors of All Saints RC School in Mansfield, Nottinghamshire, have today summarily dismissed Peter Harvey from his post at the school.”

Chris Keates , the union’s general secretary, said she was “shocked by the lack of compassion” shown to Harvey who had “dedicated the best part of his working life to the school”.

She said the teacher of more than 20 years remained full of remorse for the attack, which left the boy with a fractured skull and limited hearing in his right ear.

Ms Keates added: “He has suffered imprisonment, endured a harrowing trial and been convicted. His career is in ruins and he has no income. His wife and two school age children, all with their own health problems, have had their world turned upside down. How much punishment should one person be expected to take? The summary dismissal meted out today is further punishment.”

Ms Keates said the union was now taking legal advice about possible action.

A spokeswoman for Nottinghamshire County Council said: “We are not making any comment at this stage as there is a possibility of an appeal and we must not say anything that could prejudice that.”